Measuring carbon-energy inequality is important for assigning responsibility for climate change. At a global [@piketty_carbon_2015 @kartha_carbon_2020 @gore_extreme_2015 @hubacek_global_2017-1 @oswald_large_2020], regional [@ivanova_unequal_2020], and within-country level [@wiedenhofer_unequal_2017 @golley_income_2012 @steenolsen_carbon_2016 @weber_quantifying_2008 @hardadi_implications_2020 @oswald_large_2020], energy consumption and carbon emissions can be highly unequal across income groups. The reduction of carbon-energy inequality is not a meaningful goal by itself, however. With more nuance on carbon-energy inequality, when carbon-energy intensities of income groups can be estimated using information on different consumption baskets and technologies, we have seen that in Europe, just bringing carbon-energy intensities of all income groups in line with the top group would reduce the carbon-energy footprint but *increase* carbon-energy inequality. That lower-income groups tend to have higher carbon-energy intensities is an important finding from the environmental Kuznet's curve literature [@berthe_mechanisms_2015 @scruggs_political_1998]. We find that this is the case for Europe as a whole (although not necessarily within each European country) [@sommer_carbon_2017 @kerkhof_determinants_200]. Responsibility for climate change focuses on aggregate carbon-energy inequality, and thus tends to focus on reducing over-consumption at the top. Without differences in intensity included, where/what to target: aggregate consumption a problem at top, not at bottom, etc. [@bianco_understanding_2019]
Carbon-energy footprint inequality is increasingly being estimated in order to assign responsibility for climate change. At a global [@piketty_carbon_2015 @kartha_carbon_2020 @gore_extreme_2015 @hubacek_global_2017-1 @oswald_large_2020], regional [@ivanova_unequal_2020], and within-country level [@wiedenhofer_unequal_2017 @golley_income_2012 @steenolsen_carbon_2016 @weber_quantifying_2008 @hardadi_implications_2020 @oswald_large_2020], energy consumption and carbon emissions are often highly unequal. The proposed remedy for this is often a call to reduce the inequality by reducing over-consumption, especially by the richest at the top of the income distribution, which would then also reduce the carbon-energy footprint, everything else held equal.
Understanding this relationship is important towards achieving two potentially conflicting goals in Europe: carbon-energy footprint reduction and providing minimum energy use for decent living to everyone. At a global level, achieving sweeping poverty reduction in many regions of the world could put at risk hitting global climate targets (Hubacek). In the European context, although less unequal than the globe as a whole, lower-income groups will look to increase income, consumption, energy use, and carbon emissions will increase if more efficient and cleaner technology is not adopted at the appropriate rate. Achieving an average per capita energy use and carbon footprint in Europe in scenarios that reach the Paris agreement goals, means either doing so at current inequality levels and keeping lower-income groups near or below minimum energy use levels for decent living, or reducing economic inequality. We have shown that achieving both scenario targets and minimum energy levels likely requires reduction in economic inequality (consumption inequality reduction measures in Europe) coupled with the appropriate targeted climate-energy measures for the various income groups and countries (expand on how it relates to 1st paragraph).
Important information is also the intensity structure however. The carbon-energy intensities of consumption tend to differ between economic groups, due to different consumption baskets and different access to technology. That lower-income groups tend to have higher carbon-energy intensities is an important finding from the environmental Kuznet's curve literature [@berthe_mechanisms_2015 @scruggs_political_1998], but these findings are often not integrated with the carbon-energy footprint inequality literature that focuses on assigning responsibility based on aggregate footprint inequality.
We have found that lower-economic groups in Europe as a whole have higher carbon-energy intensities of consumption (although this is not necessarily true within each European country) [@sommer_carbon_2017 @kerkhof_determinants_200]. These higher intensities come almost entirely from domestic electricity production and heating/cooling for shelter, in a handful of Central and Eastern European countries. This is of course already an important focus of European climate policy and should be a major priority for investment fund allocation going forward, especially within the framework of the EU's European Green Deal [@bianco_understanding_2019]. Bringing intensities of consumption for all economic groups in line with those higher-economic groups in Europe with access to the cleanest and most efficient available technologies, would substantially reduce the European carbon-energy footprint, everything else held equal.
The unequal intensity structure complicates clear statements on carbon-energy footprint inequality however. We have shown that in an important sector such as shelter, lower-economic groups have almost the same level of footprint as higher-economic groups despite a fraction of the expenditure, because of their higher intensities. This can then be misleading in terms of assigning responsibility for climate change. Bringing carbon-energy intensities of all economic groups in line with the top group, and removing the inequality in intensity structure, would reduce the carbon-energy footprint, all else held equal, but *increase* carbon-energy inequality. The reduction of carbon-energy inequality is not a meaningful goal by itself.
At current European economic inequality, European carbon-energy footprint reduction in line with 1.5°C decarbonisation scenarios could theoretically be achieved at the mean. However, current economic inequality becomes a likely barrier to achieving both these scenario targets, and providing minimum energy use (and carbon) for decent living to every European. At a global level, achieving sweeping poverty reduction in many regions of the world could put at risk hitting global climate targets (Hubacek). In the European context, although less unequal than the globe as a whole, if/as lower-income groups increase their income and consumption, energy use, and carbon emissions too, will increase if more efficient and cleaner technology is not adopted at the appropriate rate. Achieving an average per capita energy use and carbon footprint in Europe in scenarios that reach the Paris agreement goals, means either doing so at current inequality levels and keeping lower-income groups near or below minimum energy use levels for decent living, or reducing economic inequality. We have shown that achieving both scenario targets and minimum energy levels likely requires reduction in economic inequality (consumption inequality reduction measures in Europe) coupled with the appropriate targeted climate-energy measures for the various income groups and countries (expand on how it relates to 1st paragraph).
